Supercharger control system



' A. J. LARRECQ SUPERGHARGER CONTROL SYSTEM Filed July 13, 1942 a4' as Jan. l5, 1946.

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STATES sUrEacHAnGEs co Anthony J. Lai-reed, Indlpolis, End.,

t ft srs assigner to General Electric Company, a corporation of New York y Application .luly 13, 1942. Serial No. 450.8% claims. (ci. sae-1.5)

in connection with aircraft for operation atv high altitudes, for example, altitudes of the order oi 8,600 feet and higher, it is known to provide a supercharger for supplying air to the cabin of the aircraft to maintain in the cabin a pressure ci a desired value.

My invention relates to the operation and con-v trol of such superchargers and has for its object to provide an improved supercharger control system.

For a consideration oi' what I believe to be novel and my invention. attention is directed to the following specification and the claims appended thereto.

In the drawing, Fig. 1 is a diagrammatic view of a system embodying my invention, and Fig. 2 is a detail sectional view on a large scale of a servo-motor used'in the system.

Referring to the drawing, I indicates the cabin of an aircraft to which air is supplied through a conduit 2, one end oi' which opens. into the cabin and the other end of which is connected to the discharge conduit 3 of a centrifugal compressor K or supercharger Ii, the inlet conduit of which is indicated at 5. 'Conduit 5 may take airvfrom any suitable point, for example, from a ram facing into the slip stream of the aircraft.

The desired pressure is maintained `in the cabin by a suitable adjustable automatic discharge valve. This is indicated diagrammatically as comprising valve head 8 controlling an opening 'I in the cabin wall, and having its stem connected to Sylphon bellows 3 which is carried by a fixed support 9 and is subjected to cabin pressure. The cabin pressure acting on bellows 8 collapses the bellows to an extent such that valve head 6 is positioned to permit escape of air from the cabin at a rate to maintain in the cabin the desired pressure. If the pressure in thc cabin decreases below the desired valueVthe discharge valve automatically closes to prevent further escape of air from the cabin. The automatic discharge valve and its manner of functioning form no part of my present invention. Such valves are known. Accordingly, it has been illustrated only diagrammatically. It will be understood that my invention is to be carried out-in connection with an aircraft cabin having an vautomatic discharge i. ings.

speed iiuid couplings A and i3.v The fluid couplings are alike in structure. The coupling B is shown in section and will be described. It comprises a hollow shaft I t mounted in suitable bear.- ings Il carried in spaced walls I8 and I9 and on which is xed the driving member 20 of the hydraulic coupling. The driven-member l5, of the coupling is carried on a bearing 2l on shaft i8 and carried by the driven member is a housing 22' supported by a, bearing 23 on shaft I8. Gear I3 is carried by housing 22. Fluid, in the present instance oil. is supplied to the coupling from hollow shaft I6 through an inlet opening 26 and it is discharged from housing 22 through a' discharge` opening 25. At 26 are openings through which oil is 4feci to lubricate the bear- Corresponding parts of the other fluid coupling A. insofar as they show on the drawing, have been indicated by corresponding reference characters with the exponenta added.

The uid couplings are shown diagrammatically. Their specic construction forms no part of the present invention. Such variable speed iluid couplings are known. The speed at which the driving member drives the driven member varies with the amount of oil supplied to the coupling so that by increasing and decreasing the ow of oil to the coupling, the speed voi? the valve which functions in the manner indicated and is capable of being adjusted or which adjusts itself automatically for the desired cabin pressures at various altitudes.

The compressor or supercharger @may be of any suitable type, a rotary centrifugal compres- Ysor being indicated in the present instance. It

comprises a shaft I on which is mounted the compressor impeller and which is driven through a gear wheel I l fixed on shaft I0. Gear wheel driven member of the coupling is correspondingly increased and decreased.

Oil is supplied to the interior of hollow shaft I6 through a conduit 2l connected to shaft I6 byv a nipple 28 provided with a bearing sleeve 29 in which runs a reduced end 30 on shaft I6. Similarly, oil is suppliedy to the interior of shaft I 6 through a. conduit 3| by a nipple 28a. Conduits 21 and 3l are connected to thev casing of a, two-way valve 32 which in one position connects an oil supply conduit(33 to conduit 3l and in the other position to conduit 2l. On the 4left hand ends'of shafts I3 and IG are minions 3d and 35 which mesh with a gear wheel 36 carried by a driving shaft 31. Shaft 3l may be driven from an aircraft engine. shaft (not shown) through suitable coupling, -which means that the driving shaft 3l is driven at variable speeds hav- .ing no denite relation to the desired superthe requirements for air for the cabin, is driven II meshes with two ring gears I2 and I3 fixed to the driven elements I4 and I5 o'i two variable from a shaft the speed of which varies in accordance with requirements for driving the aircraft. Pinion 35 is larger vin diameter than pinion 3l whereby uid coupling A gives a lower speed ratio between the driving shaft 3l and the driven shaft IU than does fluid coupling B.

T-wo-way valve 32 maybe of'any suitable construction and operated in any suitable way by means responsive to the speed of the driving shaft, i. e.. shaft 31. In the present instance, I have shown valve 32 as being operated by a speed governor 38 driven by gearing 38 from shaft I8, shaft |8lbeing long enough sothat the gearing may be located between wall |8 and nipple 28. Te spindle 48 of the speed governor is connected to the pilot valve 4| of an oil pressure-operated servo-motor, the cylinder and piston of which are shown at 42 and 43. The stem 44 of the servomotor is connected to two valve heads 48 and 48 located in the casing of valve 32 and operating to shut oi! the ilow of oil from supply conduit 33 to conduits 21 and 3|, respectively. The valve heads have two positions, the position shown in the drawing wherein valve head 48 covers the end of conduit 3i and valve head 45 uncovers the end of conduit 21 thus connecting supply conduit 38 to conduit 21, piston 43 being in its up position in cylinder 42, and the reverse position wherein valve head 45 covers the end of conduit 21 and valve head 48 uncovers the end ofA conduit 8|. piston 43 being in its down position in cylinder 42. Oil pressure is supplied to the servo-motor by a pipe 41 which connects the pilot valve to oil supply conduit 38.

Speed gov'ernor 38 is shown diagrammatically.

- The arrangement is such that as long as the speed remains below a certain value, the speed governor spring holds the governor weights from Iilying outward and the pilot valve stands in the position shown in the drawing to admit nuid pressure beneath piston 43 to hold the piston in its upper position. When the speed exceeds such certain value, the governor weights ily outward, moving pilot valve 4I upward to admit oil pressure to the upper end of cylinder 42 to eilect movement of piston 43 downward to reverse the positions of valve heads 48 and 48.

Oil pressure is supplied to conduit 33 by an oil pump 48 driven from shaft 31. Pump 48 takes ,A oil from a sump (not shown) through a pipe 48 y anddischarges it to conduit 33 through a conduit 8l and a pressure relief and regulating valve structure 8|. The pressure relief valve comprises suitable casing 82 having therein a valve head Y 3 which is biased by a spring I4 against a seat I8. The inner end of valve head 83 is exposed to the pressure of the oil from the pressure oil pump. In case the pressure exceeds a predetersure of the oil supplied by pressure pump 48 to the regulating valve.v The regulating valve comprises a casing 51 (see Fig. 2) provided with an annular inlet-pressure chamber 88 and an annular discharge chamber I8 separated from each other by a valve seat 88. Relief valve casing 52 is connected to inlet chamber I8 by a conduit 8|. Discharge chamber 88 is connected to conduit 33 by a conduit 82. Valvevcasing. is provided with walls which denne two spaced cylinders 83 and 84 located at opposed ends of the casing on opposite sides oi valve seat 88. In the valve casing is a valve body 88 having at its two ends portions forming pistons I8 and 81 located in cylinders 83 and 84, respectively, and an intermediate portion 88 which forms the valve body proper and which cooperates with valve seat 88 to control the flow of oil from inlet chamber 88 to outlet chamber 88. The valve body is hollow and located therein is a` pilot valve 1,0 whlch'serves to control iiow of oil to cylinders 83 and 84. Fixed in the bore of the hollow valve body is a liner 1l which is cut away to provide annular pressure chambers 12 and 18 which are connected to pressure chamber 58 by passages 14 and 18 respectively, and which are covered by the head of pilot valve 10. In the valve body are openings 13 and 11 which communicate with cylinders 83 and 84 and in the valve casing are drain ports 18 and 18 which connect cylinders 33-and 84 to a point In the wall of cylinder 83 is a ver tical groove 18* which connects with drain port 18 for flow of oil to it. The ends of pilot valve head 1.8 cooperate .with the adjacent end walls of pressure chambers 12 and 13 to control iiow of oil through pressure chambers 12 and 13 and openings 18 and11 to cylinders 83 and 84. It the pilot valve moves downward the upper end of the head of pilot valve 18 moves away from the upper edge of pressure chamber 12, thus con-4 necting pressure chamber 12 through port 18 to cylinder 83, to admitoil pressure to cylinder 83 behind the piston and effect movement oi' the piston downward, the piston moving until flow of oil is again cut oil by the pilot valve head. Movement oi' the pilot valvein the opposite direction serves to connect pressure chamber 13 through ports 11 to cylinder 84, thus serving to eilect movement of the valve'body upward. When the pilot valve is in the position shown in the draw'- ing, ilow oi' oil from pressure chamber 1| to both cylinders 83 and 84 iscut olf so that the valve body is stationary. Movement of valve body 88 is limited by pistons 88 and 81 engaging the ends of cylinders 83 and 64. Drain ports 18 and 1s are relatively small iny diameter compared to ports 18 and 11 so they do not prevent the, building up of pressure in the respective cylindersto effect movement ofthe valve body; but at the same gy-time, when the valve body is stationary, permit eventually the oil to drain out of the cylinders.

This is desirable in order that the valve body may A respond promptly to the building up oi' oil pressure in one or the other of the cylinders.

The outer end of the pilot valve stem projects through the head of cylinder 68 and engages the end of a stem xed to a 'diaphragm-8|. The pilot valve stem is biased to a position in engagement with the end of stem 88 by a spring 82; Diaphragm 8| is located in a casing 8 3 and divides the casing into two chambers 84. and 88.

In chamber 84 is a compression spring 88 located between diaphragm 8| and the opposed wall of chamber 84, and connected at one end to'dia- ,phragm' 8| is a tension spring 81, the other end of which is connected to a pin 88 which extends .through the wall of chamber 84 and is pivotally connected by a bell crank lever 88 and a rod 88 to a hand control lever 9| which moves overa suitable quadrant'82 so that the lever 8l may be fixed in any adjusted position. By moving hand lever 8|, the effective action of spring 88 and 81 -on diaphragm 8| may be adjusted.

nozzle .85a ,'I'hus, chamber 85 is subjected to the f leading or higher pressure of the .pressure diiierence device and chamber 84 to the trailing or lower pressure. The operation is as follows.

' lates iiowof actuating fluid tively small change in speed. The

Assume that' the devies is operating, 'shan :1

' being driven from the engine crank shaft at a governor' 88 is shown in a position such thatv fluid coupling B is connected through valve 32 to oil supply conduit 33 so that the impeller of the supercharger is being driven by thevhigh ratio fluid coupling.V The flow of air through conduit 2 to the aircraft cabin sets up a pressure difference in the pressure dierence creating device which bears a definite relation to the rate of flow, and diaphragm 8| is positioned accordingly. Oil will be supplied through the regulating valve tothe fiuid coupling B at a rate such that the uid coupling effects driving of the supercharger impeller-at a speed to give the desired air flow. If now the air ilow increases, due to an increase in speed of drive shaft 31 or to other cause, the pressure difference applied to diaphragm 8i is increased, thus eiiecting an upwardv movement of the pilot valve 10. Upward movement 'of -pilot valve 'i8 admits fluid pressure to the undersidelof piston B7, thus raising the piston to diminish the flow of oil t ough the regulating valve, the

tapered surface of the regulating valve moving closer to the valve seat 80. 'I'his effects a decrease in the amount of oil supplied to the fluid coupling and hence` a decrease in the speed at which the coupling drives the supercharger impeller. This serves to bring the flow of air back to the desired value. yIf the flow of air from the supercharger to the cabin decreases below the desired value due to a decrease in speed of drive shaft 31 or to other cause, then a similar operation takes effect except in the opposite direction. the supply of oil to the fluid coupling B being increased to eect increase in the speed at which the fluid coupling drives the supercharger, thus increasing the flow of air to the cabin. Thus, with the above-described arrangement, the flow of air to the cabin ismaintainedat the desired value by means responsive to the rate of iiow of air, which means in turn reguto the fluid coupling. 4 Speed governor 3l is driven at a speed which is proportional tothe speed of driving shaft 31 (i. e., of the engine crank shaft).` When thel speed increases beyond a predetermined value. the weights of the speed governor $8 are thrownA outward to effect an upwardmovement ofthe pilot valve so as to reverse the position of valve heads l5 and -46. This results in cutting of! the supply ofactuating fluid to fluid coupling B and connecting the supply to fluid coupling A so that at the higherengine-or driving shaft speed, the supercharger is driven through the lower ratio fluid coupling.' The speed governor 8l -is of a type such that it moves throughout its range fromthe one position to the other upon relaarrangement shown is only by way of example. Any suitable rearrangement may be used.

The provision of the two ingshaftmay beconneotedtothesu selectively through either of two available speed ny musas; una 1m1- al the t to the chamber.

supercharger, the combination of y s on diaphragm ll, thus manually adjusting the lvolume of air supplied by the supercharger to the cabin and in its extreme position lever 8| eects closing of the regulatingv valve, thus shutting off the supply of -iiuid to the duid couplings.

Y1."he' drawing is diagrammatic. It will be un# derstood that in actual practice the mechanism shown is built into a suitable casing and that theoil which discharges past the relief' valve 53 from the fluid. coupling .and other means-is caught in the casing and returned to a sump in the casing and with which the pipe 49 may connect.

4What I claim as new and desire to secure b 'Letters Patent of the United states is:

l. In a control system 'for an aircraft cabin a supercharger, a conduit for conveying air from the supercharger to the cabin, a driving shaft, a plurality of variable speed means through which the driving shaft drives the supercharger, and means responsive tothe speed ofthe driving shaft for automaticallytransferring the drive from one variable speed means to another.

2. In a control system for an aircraft cabin supercharger, the'v combination of a supercharger, a conduit for conveying air from the supercharger to the cabin, a driving shaft, a plurality of fluid couplings through which .the driving shaft drives the supercharger, and means responsive to the speed of the driving shaft for automatically transferring the drive from one fluid coupling to another.

3. In an aircraft, the combination of a cabin,

a supercharger. a conduit for conveyingiair,

driving the superoi.' the propelling shaft for transferring lopera-v tion from one variable speed means to another.

4. Supercharger larrangement ,including the combination of a chamber, a supercharger. a conduit for conveying air from the supercharger means each including a lfluid coupling forl connecting the supercharger to the driving shaft, a source of operating fluid for the couplings, means responsive to the speed yof the driving `shaft for alternately connecting the couplings to the source, and means responsive to the flow of air through the conduit for varying the .supply of operating fluid to the couplings.

5. Supercharger arrangement including the combination of a chamber, a superchargena conadriving shaft. first and second duit for conveying air from the supercharger to the. chambena driving shaft, first and second gear means each including a fluid coupling for alternately connecting valved conduit means for conducting operating governing `mechanism changes of the driving valved conduit means responsive to speed a fluid condition in said conduit for controlling aNTaoNr .1. mannen. v

the driving shaft to the fluid to the fluid couplings, a

shaft for controlling the 4to transfer operation between the gear means, and means responsive to s 

